GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"- Swift Trigger 895479: Detection of GRO J2058+42
- GRB 190326A: Swift-BAT refined analysis - a soft-short GRB or an SGR
- GRB 190326B: Insight-HXMT/HE detection
- GRB 190326A: Insight-HXMT/HE detection
- Swift Trigger 895257: Detection of GRO J2058+42 in outburst
- GRB 190326A: MITSuME Okayama optical upper limits
- Konus-Wind observation of GRB 190324A
- GRB 190324A: Swift/UVOT Observations
- GRB 190326B: Fermi GBM detection
- GRB 190324B: Insight-HXMT/HE detection
- GRB 190324A: Insight-HXMT/HE detection
- Fermi Trigger 575278303 / GRB 190326314 / GRB190326B: BALROG localization
- GRB 190326A: Swift detection of a short burst
- Fermi Trigger 575251142 / GRB 190325999 / GRB 190325A: BALROG localization
- GRB 190324A: Swift-BAT refined analysis
- GRB 190324A: CALET Gamma-Ray Burst Monitor detection
- GRB 190323A: Insight-HXMT/HE detection
- GRB 190324A: Swift-XRT refined Analysis
- GRB190324A: MASTER OT observations
- GRB 190324A: Fermi GBM observation
- GRB 190324A: Enhanced Swift-XRT position
- Further Chandra observations of GW170817 ~581-583 days since merger
- GRB 190324A: VLT/X-shooter redshift
- GRB 190321A: Insight-HXMT/HE detection
- GRB 190324A: Swift-XRT observations
- GRB 190324A: Swift/UVOT afterglow candidate
- SWIFT GRB190324.95 Global MASTER-Net observations report
- Fermi Trigger 575160247 / GRB 190324947: BALROG localization
- GRB 190324A: Swift detection of a burst
- Fermi Trigger 575108474 / GRB 190324348: BALROG localization
- SWIFT GRB190323.85 Global MASTER-Net observations report
- Fermi Trigger 575067924 / GRB 190323879: BALROG localization
- Swift detection of LS I +61 303
- Fermi Trigger 575018216 / GRB 190323303: BALROG localization
- Correction: Chandra observations of GW170817 ~581 days since merger
- Chandra observations of GW170817 ~581 days since merger
- Swift Trigger 894268: Detection of GRO J2058+42 in outburst
- Fermi Trigger 574850558 / GRB 190321363: BALROG localization
- GRB 190114C: photometric detection of a SN component
- GRB 190320A: Swift/UVOT Upper Limits
- GRB 190320A: Swift-XRT refined Analysis
- GRB 190320A: Swift-BAT refined analysis
- GRB190320A: MASTER GRB counterpart decay
- GRB 190320A: Fermi GBM observation
- GRB 190320A: Enhanced Swift-XRT position
- GRB190320A: MASTER OT detection
- SWIFT GRB190320.05 Global MASTER-Net observations report
- GRB 190320A: Swift-XRT observations
- GRB 190320A: Swift detection of a burst
- GRB 190315A: AstroSat CZTI detection
- Fermi Trigger 574678842 / GRB 190319375: BALROG localization
- Fermi Trigger 574676902 / GRB 190319353: BALROG localization
- Fermi Trigger 574345067 / GRB 190315512: BALROG localization
- GRB190311A: MITSuME Akeno optical observation
- Fermi trigger 574140965 / GRB190313.15: MASTER Global Robotic Net optical observation
- GRB 190311A: OSN optical afterglow detection
- GRB 190311A: Swift/UVOT Detection
- GRB 190311A: Mondy optical observations
- GRB 190311A: Liverpool Telescope observations
- GRB 190311A: NOT optical counterpart
- GRB 190311A: Swift-BAT refined analysis
- GRB190305A: MASTER Global Robotic Net optical observation
- GRB190311A: OAO observations
- GRB 190311A: Mondy optical observations
- Fermi Trigger 574080135 / GRB 190312446: BALROG localization
- Improved Fermi/GBM GRB localizations
- [Hxmt-ba]GRB 190310A: Insight-HXMT/HE detection
- GRB 190311A: GMG observation
- GRB 190311A: Fermi GBM observation
- GRB 190311A: Swift-XRT refined Analysis
- GRB 190311A: TSHAO optical observations
- GRB 190311A: Enhanced Swift-XRT position
- GRB190311A: MASTER Global Robotic Net OT optical observation
- GRB 190311A: NEXT-0.6m optical afterglow detection
- GRB 190311A: Mondy optical observations
- GRB 190311A: Swift detection of a burst with optical counterpart
- GRB 190305A: Swift-XRT afterglow detection
- GRB 190305A: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind observation of GRB 190304A
- IPN Triangulation of GRB 190304A (long)
- GRB 190306A: Swift-XRT observations
- GRB 190306B: Insight-HXMT/HE detection
- Konus-Wind observation of GRB 190305A
- GRB 190306A: Tiled Swift observations
- GRB 190306A: MAXI/GSC detection
- IPN Triangulation of GRB 190305A
- GRB 190305A: Swift-XRT observations
- GRB 190305A: Insight-HXMT/HE detection
- GRB 190305A: MAXI/GSC detection
- Swift Trigger 891843 is not a GRB
- GRB 190305A: Tiled Swift observations
- GRB 190305A: AGILE/MCAL detection of a burst
- GRB 190226A: Insight-HXMT/HE detection
- Trigger 890732: Swift detection of MAXI J1631-479
- INTEGRAL observation of IceCube-190221A
- Search for additional neutrino events from the direction of IceCube-190221A with IceCube
- IceCube-190221A: Swift-XRT Follow-up Observations
- IceCube-190221A: Fermi-LAT Gamma-ray observations
- Fermi-GBM Observations of IceCube-190221A
- IceCube-190221A: MASTER Global Robotic Net optical observation